Solid alkaline detergent compositions are widely used for household and institutional dishwashing, laundering, and general surface cleaning. Such detergent compositions are commonly produced as solid cast blocks which are about 2 to about 20 kg in size. The manufacturing process employed to produce such cast blocks detergent typically involves heating an aqueous emulsion of the individual components to form a molten melt, blending the molten melt to form a homogeneous mixture, and then casting, cooling and solidifying the mixture.
One component frequently used in the manufacture of solid detergent compositions is a source of alkalinity such as an alkali metal hydroxide and/or and alkali metal silicate. Alkaline sources are known to be effective for removing soils from various substrates.
A second component frequently used in the manufacture of solid detergent compositions is a chelating agent (also known as complexing agents and sequestering agents). Chelating agents aid in maintaining solubilization of the ionic hardness components of service water such as calcium, magnesium, iron, and manganese so as to prevent the hardness components from interfering with the cleaning action of the detergent components. When using service water having a high concentration of hardness components, the use of a detergent composition with a high concentration of a chelating agent is important in order to obtain satisfactory cleaning performance.
One recognized class of useful chelating agents is the aminocarboxylic acids. These compounds are a well known class of compounds that have found uses in a variety of cleaning compositions as a chelating agent including many of the solid cast detergent compositions. However, use of aminocarboxylic acids has been limited in detergent compositions which also employ a source of alkalinity as the aminocarboxylic acids tend to react so rapidly with typical sources of alkalinity that the combination solidifies before it can be properly blended and cast.
Accordingly, a substantial need exists for a detergent composition having both an effective chelating amount of an aminocarboxylic acid sequestrant and an effective detersive amount of an alkaline source which may be readily processed in common processing equipment.